The Growl preference pane has five tabs:
The General Tab holds preferences that refer to Growl as a whole. You can set your launch options, the default display set, and enable and disable logging. You can also check for updates to the Growl system here.
You have complete control over which notifications are displayed on your computer - In the 'Applications' tab you can configure which notifications are active, their priority and which display they use.
You can set differing priorities to each notification type. This may affect the way in which your notifications are presented to you, depending on the chosen display.
Sticky notifications will stay on screen until clicked.
The 'Sticky' checkbox allows you to decide which notification types are allowed to become sticky, or even force them to be sticky. The checkbox has three states: 'On', 'Off', and 'Mixed'.
'Off' means that those types of notifications can never become sticky, even if an application requests them to be. 'On' forces them to be sticky. 'Mixed' (looks like a bar - see the screenshot above) is the default setting; it means that the application that issues the notification is allowed to decide whether or not notifications of that type should be sticky.
Display Options is where you can configure what you are shown when Growl notifies you.
First you select which display you would like to configure. Then you can change settings on each display however you wish. Some displays have priority settings, some provide preference on the transparency, etc.
To get more display styles, or make your own, visit the expanding Growl page

